Re: [PATCH RFA] tree: define tree_code_type in C++11/14 [PR108634]

[Jakub Jelinek <jakub@redhat.com>]

On Mon, Mar 13, 2023 at 04:15:12PM -0400, Jason Merrill wrote:
> The r13-6577 change to use tree_code_type_tmpl in earlier C++ dialects broke
> gdbhooks, which expects tree_code_type to always be available.  I considered
> trying to make gdbhooks more robust, but it seemed simpler to define
> tree_code_type as a reference to the template.  This still ends up with a
> definition of the reference in each translation unit, but that's allowed by the
> ODR because it always refers to the same entity, and is much smaller than
> having the whole table in each TU.
> 
> 	PR plugins/108634
> 
> gcc/ChangeLog:
> 
> 	* tree-core.h (tree_code_type, tree_code_length):
> 	Define even without inline variable support.
> 	* tree.h (TREE_CODE_CLASS, TREE_CODE_LENGTH):
> 	Only one definition.

I think it would be better to change gdbhooks.py to match what the code
does.
We should adjust the
        # extern const enum tree_code_class tree_code_type[];
        # #define TREE_CODE_CLASS(CODE) tree_code_type[(int) (CODE)]
comment because that isn't true even for new bootstrap compiler.
And, I just wonder if
        val_tree_code_type = gdb.parse_and_eval('tree_code_type')
couldn't be replaced with
        try:
            val_tree_code_type = gdb.parse_and_eval('tree_code_type')
        except;
            val_tree_code_type = gdb.parse_and_eval('tree_code_type_tmpl<0>::tree_code_type')
or so.

	Jakub